( xxii ) 



Dr. Macalister, in a letter to me, observes, that since these experi- 

 ments began many French and German physiological chemists have 

 taken them up. " What a pity," he observes, " that some of our Irish 

 chemists should not work in this perfectly new department." 



Yet, when the existence of a great Anatomical School in Dublin is 

 considered, the paucity of the biological researches which have appeared 

 in the " Transactions " of this Academy fills the mind with regret, how- 

 ever great their value may be — more especially, when contrasted with 

 the number of such Papers in the Proceedings of the Royal Society. 

 Why should not those who have the power have also the desire to follow 

 the few leaders whose example has shed a lustre on our country? Will 

 members of this Academy not assist others more largely than they have 

 hitherto done in reaping the harvest which in golden waves is stretched 

 before and around them ? 



The study of Embryology has led to many singular discoveries, and 

 has shown how closely analogous are the laws of formation with those of 

 disease. It had been held that in the early periods of existence organs 

 v^ere in their relations and form the same as in the perfect animal, 

 differing only in their size. But it is now shown that, before arriv- 

 ing at its ultimate form, an organ must undergo certain transforma- 

 tions, numerous in proportion to its complication ; so that there is a 

 passage from a simpler to a more complex form, the latter being 

 always preceded by the former. Embryology of the higher beings is 

 thus reproduced by the comparative anatomy of the lower. Thus, 

 the doctrine of organic pre-existences is overturned, so that the 

 forms of the embryo will not give us a knowledge of those of the 

 more advanced being. 



In this progressive formation, as observed by Serres, a particular 

 affinity seems to pi'eside over the arrangement of structure, each 

 organic tissue and each part of an organ being directed towards the 

 part or tissue with which it is homogeneous and only uniting with it. 



Thus nerves form themselves with nerves, arteries with arteries, 

 osseous nuclei with bone ; but we never see the kidney unite itself 

 to the liver, or the combination of a nerve with an artery. 



We might believe in following these formations that we were as- 

 sisting at a regular crystallization of different cells in which the homo- 

 geneous molecules are attracted, while the heterogeneous are repelled ; 

 and this under the influence of Life. 



